Milling Guards

[tito]

Warning: this might cause some of you machinists to cringe, but I got a lesson this morning in what maker James V. Hughey calls "farmboy machining," and I'd like to pass it on to any other knuckleheads (unless I'm the only one?) If it is unsafe, please advise. If you want to try this, please use caution and please do so at your own risk.

I have never found an easy way to make the slot in a guard. No matter what method I tried, it always took a lot of time. I'm visiting my in-laws in Anchorage right now, and this morning my father-in-law took me over to see another knifemaker he'd met here in town. His name is James V. Hughey - great guy. He showed me his method, and it just made me feel dumb as a rock for having wasted so much time over the years. Here's the method:

He uses an 8" drill press, a little desk size one, not a floor model. He chucks up a piece of square stock, brass or whatever, in a machinists vise. He centers the stock on the drill bit and clamps a brace (just a block of wood) on the drill table so he can drill a straight line of holes. Then he drills out the holes so that they overlap each other, which does most of the work for you (this is all pretty standard so far, and there's plenty of tutorials out there, some even with pictures).

I have never been able to make this method work - my drill bit usually jumps over into the next hole, or I get it crooked, etc. etc. He solves this problem by using the vise and brace, but then also chucking the drill bit up as far as it will go. He was only working with about 1.25" of bit. When he drilled the last hole, he lowered the bit all the way down and pulled the whole vise back, dragging the bit down the length of the slot. Basically he turned his drill press into a mill. Since the bit was chucked up so high, it doesn't break, and it ate through the rest of the material really easy. He was using this method n 1/4" stock. That's it, nothing fancy. In just a couple of minutes he had an undersized slot big enough to fit a file through for final fitting to the blade.

Gotta get back to my vacation - if anybody has any further advice, for safety or otherwise, please chime in.

If your advice is to use a mill for this operation, please just send me one and I'll do just that.

v/r, coty

 

[burke531]

use an end mill instead of a drill bit and it will work better yet

 

[Nathan the Machinist]

use an end mill instead of a drill bit and it will work better yet

Actually, possibly not. Reason being that endmills are designed to cut on their side and drill bits are not. Counter intuitive? The resulting "bite" and the subsequent forces generated by an endmill would require the vice be clamped to an X Y table. It sounds like he is just connecting the holes by dragging the vice back by hand. I wouldn't suggest doing anything with an endmill by hand.

But, for the record: *CRINGE*

Another way to approach this, that has the "machinist's seal of approval" is to use a chisel or a part ground as a chisel (some folks use a modified lathe tool) mounted in the spindle with the spindle break on to nibble away at the nubs and to square up the corners, using the down feed as an arbor press and some sort of chisel as a broach. You only shave off a few thou per pass. I know for a fact the spindle bearings in a Haas will tolerate this, your actual mileage may vary...

 

[Mike Hull]

Warning: this might cause some of you machinists to cringe, but I got a lesson this morning in what maker James V. Hughey calls "farmboy machining," and I'd like to pass it on to any other knuckleheads (unless I'm the only one?) If it is unsafe, please advise. If you want to try this, please use caution and please do so at your own risk.

.........................


I have never been able to make this method work - my drill bit usually jumps over into the next hole, or I get it crooked, etc. etc. He solves this problem by using the vise and brace, but then also chucking the drill bit up as far as it will go. He was only working with about 1.25" of bit. When he drilled the last hole, he lowered the bit all the way down and pulled the whole vise back, dragging the bit down the length of the slot. Basically he turned his drill press into a mill. Since the bit was chucked up so high, it doesn't break, and it ate through the rest of the material really easy. He was using this method n 1/4" stock. That's it, nothing fancy. In just a couple of minutes he had an undersized slot big enough to fit a file through for final fitting to the blade.

If you scribe a centerline where you want to drill, put a cold chisel on that line and smack it. You don't have to go crazy, just make a groove. The bit will ride in there very well.

 

[Bruce Bump]

If you scribe a centerline where you want to drill, put a cold chisel on that line and smack it. You don't have to go crazy, just make a groove. The bit will ride in there very well.

Mike, Its good to see you here again. You have been missed brotha. Where have, how have ya been? :thumbup:

 

[burke531]

Actually, possibly not. Reason being that endmills are designed to cut on their side and drill bits are not. Counter intuitive? The resulting "bite" and the subsequent forces generated by an endmill would require the vice be clamped to an X Y table. It sounds like he is just connecting the holes by dragging the vice back by hand. I wouldn't suggest doing anything with an endmill by hand.
..

Nathan, First I agree that this is not the best way to do this but for the method that he is using a center cutting end mill will work better than a drill. I myself have used this method and where he is basically drilling intersecting holes and then taking out the remaining peaks in the slot an end mill that is designed to cut on the sides should do a better job and create less risk of an accident than a tool that was not intended to cut in this manner.

 

[tito]

Thanks for your responses guys. I bought an end mill for my drill press to try this several years ago. I ended up not using it for guards, but it works well on micarta and wood to "mill" out a slot for a hidden tang (Terry Primos' technique).

One note, I didn't mention bit speed - the maker who showed me this likes "fast." I'd rather do it slow and steady. I also find that whether you use a drill bit or an end mill, the rotational force will try to "pull" your slot off to one side if you aren't careful to keep it straight on the fence/guide of your machine's table.

Someone also mentioned using a punch to keep your bit from riding over into the next hole - this is necessary, but I still couldn't keep the bit out of the next hole. BTW, Mr. Hughey uses the tip of the drill bit for a punch. He presses the bit into the material prior to turning the drill on, making a dimple just like a punch. He centers the material mostly by eye then rotates the vise 180 deg and makes a new dimple - if it's not on center, he taps gently on the table with a hammer. I like it because it saves time.

Finally, just wanted to reiterate that this maker has been using this method without hurting himself for many years. That said, after 40 something years of carpentry and building houses and working here in AK, he would likely not notice if one of those gnarly talons he calls fingers was snatched off by his drill. Please be careful.

 

[tito]

But, for the record: *CRINGE* ...

Another way to approach this, that has the "machinist's seal of approval" is to use a chisel or a part ground as a chisel (some folks use a modified lathe tool) mounted in the spindle with the spindle break on to nibble away at the nubs and to square up the corners, using the down feed as an arbor press and some sort of chisel as a broach. You only shave off a few thou per pass. I know for a fact the spindle bearings in a Haas will tolerate this, your actual mileage may vary...

I'm not sure I understand exactly. Is the spindle rotating during this operation, or are you just pressing down on the edges of the "peaks" in the slot and in the corners to square them up?

 

[McAhron]

Before I got a mill I had good success using the drill multiple holes and then clean up with a carbide cutter in a dremel.I found as long as the piece was clamped in a vise and using two hands to hold the dremel at maximum speed I could do a decent job removing the extra material and had less cleanup with a file.